There are two basic choices, both of which are dependant on whether or not you intend to spend money on the game.
There are advantages to getting some gear as soon as you can ,but you will outgrow it, and may wish you had waited till you could get better, given how hard it might be to collect the items you need, and the silver it costs to forge them
Do not build anything that is way above the level of your hero, unless you are prepared to wait to wear it.
Yes there are guides to what equipment to forge, in order to improve every skill imaginable.
Attacking invaders is a good way to get items you need,especially if you want to get the better invaders equipment, which takes even longer to do, and costs higher levels of silver.
Some of the invaders equipment is more useful than others, but you might need to wait a long time for the invader you want to appear on the global map ,in order to attack it.